John Curl's Blowtorch preamplifier part III

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Tests are saying humans do not hear H2 0.1 - 1% and H3 0.01 - 0.1% with any music samples, so why to bother.

It's funny that it is easy to design class A open-loop circuits (even simple ones) that do ~.01% distortion at even 20V p-p. So we can have all the "magic" and still get the measurements.

EDIT - hitsware, I must have been channeling your response. :)
 
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PMA, You know very well that isn't the whole truth. Existing data are for perhaps 95% of the population, and they are not hard limits.

In my view, most people simply ignore low level distortion without even knowing that is what their brains are doing. And, the way brains work it is not a simple matter of asking someone to try to change it suddenly for some test.

EDIT: Also, there are people who make errors of sighted listening. It is not an easy area to research properly due to the complexity of human brain functioning.
 
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PMA, You know very well that isn't the whole truth. Existing data are for perhaps 95% of the population, and they are not hard limits.

In my view, most people simply ignore low level distortion without even knowing that is what their brains are doing. And, the way brains work it is not a simple matter of asking someone to try change it suddenly for some test.

The 95% / 5% - that's still a hypothesis, not proven. And "ignore" - well - perception is very complex. Both the ear and the eye add distortion, by objective standards, and the overall sensory process isn't at all understood. Perhaps those 5% have more, or less.. innate ear distortion, or have learned to hear stuff others ignore.
When I was working on video compression stuff, I learned to see artefacts that no one untrained would notice, and to see the flicker in frame rates that should be invisible. Took a while to "forget" that! So would it be better, teaching the "5%" to be like the "95%" rather than the other way around, if you see what I mean..?
 
It's funny that it is easy to design class A open-loop circuits (even simple ones) that do ~.01% distortion at even 20V p-p. So we can have all the "magic" and still get the measurements.

EDIT - hitsware, I must have been channeling your response. :)

In fact, less than 0.001% at 20Vp-p. I doubt the race for lowest distortion and would vote for "unconditional" stability with all possible kinds of speaker complex load.
 
... a monotonically decreasing distortion spectra is preferred...

This is but ONE single school of thoughts, with some publicity from Jean Hiraga in France. These guys think that since a musical instrument has a lot of harmonic content (monotonically decreasing or otherwise), an amplifier should do the same.

That reminds me of the Bose 901 joke of the 70's: the idea is in a concert hall, the audience hear about 10% direct sound and 90% reflection, so Dr. Bose went on building a box with 1 speaker facing forward and 8 speakers facing back.

Of course they're all dead wrong.

... So my conclusion is audio has no connection for this group to EE...

Perfect wording: for this group and this group only.
 
The 95% / 5% - that's still a hypothesis, not proven.

It was a statement from Earl Geddes who did a lot of research in that area. I will trust his expert opinion on that.

EDIT: Regarding whether it is better to ignore common deficiencies of reproduction systems, I think it is an interesting question. For the past few months I have been trying to work on it from the other end, that is, to reduce some deficiencies. Turns out to be a lot of work :)
 
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John,

Erno Borbely and I believe Nelson Pass have both commented on cascoding being useful for jfet voltage and current gain stages, but cascoding FET current gain stages such as an output stage driver, while resulting in lower distortion, were also percieved as less dynamic sounding. Erno tired cascoding the output devices it in a couple of late 80’s preamps to lessen the difference in the 2SK216/2sj79 devices, but gave up on the idea after negative customer feedback on the dynamics issue.
 
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